AND DESCRIPTION OF RELATED ART, INCLUDING INFORMATION DISCLOSED UNDER 37 C.F.R. 1.97-1.99
Power door drives or operators for mass transit vehicles are in widespread use throughout the world. The systems now in use can be broadly divided by the specific energy source for the system prime mover or door drive. The invention disclosed herein pertains generally to door drives employing electrically powered devices as prime movers.
Generally speaking, electrical drives utilize highly reliable rotary electric motors operating doors through intermediate devices. These intermediate devices convert rotary motion of the drive motor to linear and/or other movement required to move the vehicular door panels. Intermediate devices as contemplated herein can further be categorized as mechanical linkages or rotary helical drive systems.
While reliable and reasonably cost effective, a major shortcoming of the above described drive systems lies in need for an intermediate component between the prime mover and door panel. At a time where system reliability is an increasingly important factor in choosing door systems, the use of a prime mover such as a linear induction motor which directly drives the panels, essentially eliminates much of the intermediate linkages, thereby substantially increasing the reliability of the overall system.
Linear induction motor (LIM) drives have been proposed as door panel drives for some time. U. S. Pat. No. 1,950,627 discloses and claims such a system. However, as disclosed in U.S. Pat. No. 1,950,627 the system as disclosed, generally speaking, would be inoperative and/or impractical due to the space and power limitations currently present in mass transit vehicles.
Further, previous innovations disclosed under prior art patents using LIM drives did not contemplate other requirements mandated by public transportation car manufacturers and municipal or federal authorities. Additional requirements such as: reliable mechanical lock device, immunity against iron dust with simplified mechanical design resulting in reduced maintenance, ability to conform to a restricted mounting space and envelope, door panel obstruction detection capability, reliable emergency door opening mechanism and smooth door opening and closing speed profile.
Applicant, however, has discovered an approach to integrating presently available linear induction motors into modern complex door control systems required by today's transit authorities.
It is, therefore, an object of the invention disclosed herein to provide a door control system for mass transit vehicles wherein the combination of electrical control and door drive components has high reliability through reduction in the number of components employed.
It is an additional object of the invention to provide a door drive wherein the prime mover drive forces are directly applied to the drive panel.
It is a further object of the invention disclosed herein to provide a door drive prime mover wherein components intermediate the prime mover energy source and drive door panel are reduced to one moving part.
It is yet an additional object of the invention to provide an electronic control for a linear induction motor door drive wherein door edge force and door speed are controlled with direct electromechanical devices.
It is an additional object of the invention to provide a door drive incorporating a LIM motor having drive powered door opening lock.